The present invention relates to compositions of rebond foam. The present invention particularly relates to flexible polyurethane rebond foam compositions.
Polymer foams, particularly flexible polymer foams, can be fabricated into objects having useful shapes. For example, flexible foams can be molded or machined into shapes useful for preparing automobile seats, bedding, and the like. Flexible foams can be used in carpet and furniture production as well as in the manufacture of toys and the like.
However, in processes for preparing shaped polymer foams, waste foam can be produced. The waste foam can be from the fabricating process and represent the area/volume of the foam removed from the starting block stock to form the shaped foam object. Or, the waste foam can be just the off-specification products which are occasionally produced in some fabricating processes.
Whatever its source, waste foam production is usually undesirable. The waste foam can represent materials which must be discarded and not sold. In some areas, landfill space has become scarce and the cost of disposing of waste foam has become very high.
There have been efforts to re-use waste foam production, particularly waste and scrap from the production of flexible foams. Flexible polyurethane foam scrap can be chopped and then coated with a binder consisting of a polyisocyanate prepolymer having isocyanate functionality, and a catalyst. The coated, chopped foam is compressed and then treated with steam to cure the binder to form a rebond foam sheet or other shape.
In another process for using flexible polyurethane foam waste, the flexible foam waste is cryogenically ground and blended back into the formulation used to prepare it. The ground flexible foam can be used at a level of about 20 percent within the polyol component of the polyurethane foam formulation.
However, preparing materials including waste foam is not always trouble free. The resultant materials may have inferior physical properties. Or the materials so produced can have imperfect finishes which will not permit its use in external and visible applications.